The present invention relates to an image forming apparatus wherein various post-processing operations can be carried out by a sheet post-processing apparatus for a sheet on which recording has been conducted by an image forming apparatus body, to an intermediate conveyance unit that is located between the image forming apparatus body and the sheet post-processing apparatus to be connected to both of them, and to an image forming method.
In Patent Document 1, there has been disclosed an image forming apparatus wherein various types of post-processing apparatuses having functions to conduct hole-punching processing, stitching processing, folding processing and bookbinding processing for a sheet after recording can be mounted on a copying machine serving as an image forming apparatus body.
An image forming apparatus shown in Patent Document 2 is one wherein a common single-sheet processing unit is arranged between an image forming apparatus body and at least one type of post-processing apparatus among plural types of post-processing apparatuses.
In the case of the image forming apparatus described in Patent Document 1, the apparatus is constructed so that various types of post-processing functions may be handled by a single post-processing apparatus. Therefore, the image forming apparatus is effective when it is installed in the environment where various users use the apparatus in many ways, as in an office, for example. Since the post-processing apparatus of this kind is relatively small in size, it is also effective on that point for an office where space-saving is required.
When using as an image forming apparatus for such as quick printing, for example, an image forming apparatus that satisfies all post-processing functions is not always needed, and an apparatus having capability to satisfy only-specific post-processing function sufficiently is required. Namely, when using an image forming apparatus for such as quick printing, the frequency for a specific user to use specific post-processing function is higher than that for various users to use in many ways as in an office.
In the aforesaid image forming apparatus, a single relatively-compact post-processing apparatus has various post-processing functions and it deals with various usage types. However, when focusing attention on individual post-processing function, it is rather difficult to assure that the individual post-processing is at sufficient level functionally. For example, when using an image forming apparatus as an image forming apparatus for quick printing, the required level is higher than that of post-processing requested on an image forming apparatus used in the office, and the actual level is still lower than the level satisfying sufficiently the demands in the quick printing.
In recent years, an image forming apparatus of an electrophotographic system has come to be used in the field of quick printing. Namely, book binding on a print-on-demand system of “making prints in necessary quantity of copies only when needed” is possible, by using an image forming apparatus equipped with the post-processing apparatus stated above.
In addition, no labor hour is needed for plate making which has been carried out in the conventional printing, and enhancement of efficiency and cost reduction for bookbinding work are greatly expected.
The image forming apparatus shown in Patent Document 2 is an apparatus satisfying the aforesaid demands, and it is an image forming apparatus having the structure wherein a single sheet processing unit representing one type of post-processing apparatus is connected on the sheet ejection side of the image forming apparatus body, and further, at least one type of post-processing apparatus among plural types of post-processing apparatuses is connected to the single sheet processing apparatus.
(Patent Document 1) Unexamined Japanese Patent Application Publication No. 2002-128384
(Patent Document 2) Unexamined Japanese Patent Application Publication No. 2005-15225